Electric smelting-furnace.



E. R. TAYLOR.

ELEGTRIO SMBLTING FURNACE.

LPMIGATION FILED JUNE 12, 1908.

Patented 0011.26, 1909.

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E TAYLOR.

ELECTRIC SME TING FURNACE.

QPLIOATION FILED JUNE 12, 1908.

Patented Oct. 26, 1909.

10 SHEETS-SHEET 2 Qvwentoz l/vi in zoom E. R. TAYLOR,

ELECTRIC SMELTING FURNACE.

APPLICATION FILED JUNE 12, 1908.

938,35 1 Patented (Mat. 26, 19%.

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, ELECTRIC SMELT APPLICATION FILE 2, 1908; 938 ,35 1 Fa -tented Oct. 26, 1909.

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E. R. TAYLOR. ELECTRIC! SMEL'IING FURNACE.

APPLIOATION FILED JUNE 12, 190B- Patented 26 10 SHEETS-SHEET 6.

EfRLTAYLOR. ELEOTRIU EMELTING FURNAUE.

I APPLIOATION FILED JUNE 12. 1908. 938,35 1. Patented Oct. 26, 1909.

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APPLICATION FILED JUNE 12, 1908.

Patented Oct. 26, 1909.

10 SHEETS-SHEET 7.

luvanfoz W5 in 20mm E. R. TAYLOR. ELECTRIC SMELTBIG FURNACE. APPLIOATION FILED JUNE 12, 190B.

Patented Oct. 26, 1909.

10 SHEETS-SHEET 8.

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ELBO'IRIO SMELTING FURNACE.

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Patnted 0ot.26,1909.

10 SHEETS-SHEET 10.

wane/Mao EDWARD R. TAYLOR, OF PENN Y AN, NEW YORK.

ELECTRIC SMELTING-FURNACE.

Specification of Letters Patent.

Patented Oct. 26, 1909.

Application filed June 12, 1908. Serial No. 438,115.

-- used for etfecting other reactions and reductions.

The present invention consists in the improved electric furnace hereinafter described, and certain novel features thereof,

'as more particularly set forth in the claims hereto appended.

The invention is in part tltltlll'lm'izll to the Improvement in electric furnaces set forth in my specit'watiou forming part of United States Letters Patent No. (388ml, dated December 10,1901.

The objects of the present invention common thereto and to said patented improvement, include. the protection of horizontal or substantially horizontal electrodes against excessive wear, and the regulation of the electric action within the furnace by means of fragmentary conducting or resistance regulating material, fed by gravity upon said electrodes and between the same; the prevention of the leakage of electricity, with reference to securing the maximum heating or electrochemical effect of the current; the. cooling of the electric conductors 5 or electrode stems; the interception and utilization to the utmost of heat that would otherwise be lost by radiation; and the avoidance of the cooling of the more highly heated linner part of the furnace or heat zone, in continu'misreactions and reductions,

by the sudden introduction of cold material, so as to lnsure the continuity of the oper- Other objects common to said patented improvement and the present invention are to utilize in an effective manner the alternating or two-phase electric current, and to provide for varying the paths of the elec- Other objects, including most of those hereinafterstated, are common to the preseutimprovement and to a companion improvement in the Art of electric smelting moreparticularly described and claimed in a companion specification forming part of a divisional application for patent tiled March 3, 1909, Serial No. 481,121.

The leading object is to overcome certain ditliculties that present themselves in the electric smelting of metals and other electrically conductive materials in a shaft furnace, and especially to keep the material of the charge between the electrodes from becoming so conductive of electricity as to reduce the resistance of the furnace below practicable working limits.

Other objects are the separation of the ore in the four quarters of a two-phase furnace having two pairs of horizontal or inclined main electrodes, hereinafter referred to in common as horizontal, arranged in vertical planes at right angles to each other, so as to keep the same separate, and thus to facilitate the manipulation of the ore within the furnace; to provide for employing a large proportion of fine ore, such as cannot be smelted in a blast furnace because of its liability to be blown out of the furnace by the blast; to provide for feeding fine and coarse ore downward in a stack furnace in separate vertical or substantially vertical columns; to utilize a. portion of the, charge and especially the fine ore columns for the conservation of the heat of the furnace, by feeding the same downward at or near the periphery of the furnace to a suitable point. above horizontal main electrodes, and there feeding the same inward by a stoking operation to so regulate the feed of such material as to properly utilize the energy liberated between the main electrodes without causing short circuits; to provide for admitting successive small quantities of. fine ore into the outer edges of the coarse ore columns in order to gradually bring the hottest of the fine ore in toward the center of the furnace, and to relieve the stress of stoking to that extent; to provide for feeding suitable carbonaceous material, preferably eit-her coke or charcoal, in a central column, and for utilizing lateral wings of such coke column, as it is hereinafter termed, to separate the columns of coarse ore; to utilize such coke column as a resistance conductor between secondary electrodes located at the bottom and top' of the furnace respectively; to provide in this way for starting the furnace with facility by the interaction of said'secondary electrodes and said coke column; to keep the carbonaceous material of the charge incandescent to a greater height than has heretofore been practicable; to vary the height of such incandescence atwill; to determine thus the percentage of carbon, for example, in the.

reduction of iron, so as to produce pig iron or steel as may be desired; to insure the reduction of ore to metal, to as considerable an extent as may be possible, in the fine ore before it reaches the heat zone, and to utilize continuous contact between the carbon of which they are mainly composed and their metallic stem portions.

Another object is to provide for feeding inward the resistance regulating material at will, by stoking, to regulate the conductivity of the charge.

Another object is to provide, by the orestoking means or independently, for the introduction of oxidizing material into the center of the furnace, for the purpose of oxidizing accumulations of carbon or other oxidizable materials which may at times form to an undesirable amount and interfere with the regular working of the furnace.

Other objects peculiar to the present improvement andsaid companion improvement in the art of electric smelting relates especially to the production in an electric furnace of iron or steel, hereinafter referred to in common as metal, from iron ores consistingof or containing sesquioxid of iron, Fe O or magnetic oxid, Fe or other forms-of iron oxid adapted for like treat-- ment. SesquioXid of iron, for example, at a snflicient but low temperature, in contact with carbonic oxid gas also at a low but sufficiently high temperature, undergoes substantially the following reaction, that is to say In the production of iron in a blast furnace the above reaction is usually completed before the material reaches the high tempercertainty and difficulty; and it is one object of the present invention to furnish conditions whereby the above reaction will be accomplished in the regular order of the descent of the material from the feed hopper to the heat zone. In the first heating-up of an electric furnace of this kind, as the coke, charcoal or other carbonaceous material is brought to incandescence, by the resistance it offers to the passage of the current, any oxygen within reach will be absorbed, with the formation of carbonic acid ((10,), which gas in the presence of an excess of incandescent carbon speedily becomes re duced to carbonic-oxid gas (CO) one molecule of the carbonic acid becoming two molecules of the carbonic-oxid gas. This latter gas then coming in contact with the oxid of iron, in any of its oxid forms, at a sufficiently high. temperature, absorbs oxygen from the ore, with the reduction of the ore to metal, and the formation of one mole cule of carbonic acid for each molecule of carbonic-oxid gas. If the carbonic acid thus formed can again be brought into contact with incandescent carbon, and the resulting carbonic oxid gas againbronght into contact with iron ore, the same reactions above described will repeatedly take place; and angother ob ect of this invention is to so circulate these two gases as to repeatedly bring the carbonic oxid gas as quickly as practicable after its formation into contact with iron ore in its proximity, and afterward, as soon as possible thereafter, to bring the carbonic acid thereby produced into contact with incandescent carbon, and to repeat the cycle of these reactions until the final gas passes out of the furnace at its top.

Other objects will be set forth in the gencral description which follows.

Ten sheets of drawings accompany this specification as part thereof.

Figures .1 and 2 represent axial vertical sections in different planes through an electric smelting furnace embodying the present invention, and illustrating the smelting process; Fig. 3 represents the same vertical section as Fig. 2, showing the furnace empty; Figs. 4 and 5 are plan views respectively of the top of the furnace above and beneath its top plate, indicating by lines AB and CD the planes of Fig. 1 and of Figs. 2 and 3, respectively; Fig. 6 represents a horizontal section on the lines EF, Figs. 1 and 2 and Fig. 3; Fig. 7 represents a horizontal section through the empty furnace on the lines G-H, Figs. 1, 2 and 3; Fig. 8 represents a detail view of the secondary electrodes at the top of the furnace, on a larger scale partly in section on said lines A-B, Figs. 4c and 5; Fig. 9 represents a sectional side view of one of these electrodes on a still larger scale; Fig. 10 is a fragmentary'face View projected from Fig. 9; Fig. 11 represents a cross section one o the stoking screws enlarged from Fig.

3; Fig. 17 represents a face view partly in section on the line OP, Fig. 16.; Figs. 18, 19 and 20 are diagrams representing the paths of the electric current under different conditions; and Fig. 21, Sheet 6, is a frag- F naentary detail View illustrating a modifica tion hereinafter described.

Like reference characters indicate like parts in all the fi ures.

The improved urnace is of a stack form; its internal structure, a, being builtof suitable brick or the like within'a metallic shell, I), of iron or steel, hereinafter referred to as iron; and a layer, 0, of a suitable non-conductor of electricity, such as asbestos, being interposed between the internal structure a and the shell 6 throughout. The top plate, (Z, of the shell 6 and of the furnace is conveniently horizontal, and is provided with feeding hoppers, e, f, g and h, best shown in Fig. 4, which are so shaped and so united with each other and with the top plate by braces, stays and angle irons, represented respectively at 1, 2 and 3, as to form a truss by which the subjacent top-plate is stiffened against sagging. The respective hoppers e, f,.g and h communicate with the upper ends of flue-shaped passages, 2', 7', 7.: and l, which extend downward within the internal structure a and the hoppers f and passages 7', each of them four in number in the spe- CIfiC construction represented .by the. drawmg, are appropriate to the principal charge of ore, hereinafter referred to as the coarse ore, which is thus divided into several distinct columns. Another set of said hoppers and passages, g" and 7c, external to said coarse-ore passages, are appropriated to fine ore,-.which may be of that description which is too fine for reduction in a blast furnace, and which is utilized in this arrangement, not only to feed fine ore into the charge, as hereinafter more particularly set forth, but also and primarily to conserve the heat of the furnace by intercepting and utilizing heat that would otherwise escape by radiation and b being conducted outward, and to carry tie same back into the working chamber so. as to protect the iron shell of the furnace against excessive heat, and to utilize such radiant or outwardly directed heat in the reduction of the ore.

The fine-ore passages 1c are divided into inner and outer passages by hollow walls forming a gas space, m, Figs. 2, 3, 6, 7 and 15, within each Wall, open at bottom and in direct communication with said coarse-ore passages j and with the working chamber, n,

by way of outwardly flaring gas tubes, 0, hereinafter more particularly described. The

outer fine-ore passages, marked commu-,

nicate with the working chamber at their lower ends only, and are located peripherally, as shown in Fig. 6, so that the body of fine ore within them may be as cool and as continuous as may be practicable, with reference to intercepting and utilizing outwardly directed heat. The inner fine-ore passages 70 are provided with baflie plates, p, igs. 2, etc., preferably V-shaped in crosssection, and arranged with the apex uppermost so as to retard the flow of the fine ore to a sufficient extent without being subjected to breaking strains, and more particularly to form suitably distributed spaces throughout the body of fine ore. Fromeach of these .s aces an o enin Fi s. 3 and 15 extends inward through the wall of the working chamber n, and affords a discharge for more or less of the fine ore as it reaches that point into the outer edges of the coarse-ore columns, so as to gradually mix the two as they approach the heat zone, and to gradually bring the hottest of the fine ore inward toward the center of the furnace and thus to reduce the need of stoking.

The central hopper'e and the passage 2' extending vertically therefrom are appropriated to suitable dry carbonaceous mate rial, which may consist wholly or in part of charcoal or coke and is hereinafter referred to as coke. The coke column so formed is intended to preserve itsidentity from top to bottom of the furnace in the initial charge,

and from the top to the fluid contents of the hearth when the furnace is in operation,

as in Figs. 1 and 2. Said coke passa e i is formed by a central circular wall at t e top of the furnace, and this wall is supported,

as shown in Fi 3, by partition walls in the form of flying uttresses, arranged in pairs around said central wall,and forming between them where their inner edges are exposed below said circular wall, a wingshaped'passa'ge, i, in communication with said central passage i, above each of the main electrodes, 9, 1", s, and If, so that the coke may spread laterally in the form of wings between and below said partition walls, and extend the separation of the columns of coarse ore as hereinafter described.

The other four of said hoppers, shown at h I in Figs. 1 and 4, and theperipheral. pascharge at the heat zone as set forth in the r carbon and molasses; after which this strucprevious specification hereinbefore referred to. I still prefer as such material broken electrode rarbons reduced to suitable fragments so as to feed by gravity, which insures a regulating material of greater conduc'tivity than the charge of coke or charcoal. To insure the discharge of said regulating material as required, the iron shell 7) and its linings are provided with suitably capped stoke-holes, 4, Fig. 1, in communication with the. working chamber n. beneath the several passages Z, and so arranged as to facilitate pushing the regulating material inward over the main electrodes (1. r, s, and L, respectively, from time to time as may be necessary. Said main electrodes 9, r, s, and 1., are preferably four in number and arranged in two pairs at right angles to each other and horizontal as aforesaid. They are located immediately above the hearth, u, and each of them in the specific construction shown in the drawings comprises a carbon body, 5, preferably built up of relatively small carbons, and securely united with ample electric contact to a metallic stem, 6, preferably of aluminum. Each of these electrode stems extends outward through a water-copied stufiing box, 7, which is mounted on a face-plate, 8, covering an opening through which the body of the electrode may be introduced and withdrawn, and detachably secured to the iron shell 7). Insulation against the leakage of electricity is introduced between the electrode stem and the gland of the stulfing box, and between the face-plate and iron shell, either or both.

Secondary electrodes, '0 and w, are located respectively at the bottom and top of the furnace; the bottom electrode, '0, having a carbon body, 9, which forms a lining for the hearth 'u. of the furnace, and is connected with a depending central metallic stem, 10, preferably in a peculiar manner which is illustrated by Figs. 12, 13 and 14. As here shown the electrode stem, 10, terminates at top in a large flat contact disk, 10, which is bolted to a contact-forming back plate 11 within the carbon body 9. Into this back plate 11, preliminarily, are cast fast the lower edges of upwardly extending clamp plates 12, of expanded plate-metal or the like, arranged in pairs, with suliicicnt space between the several pairs to admit, tightly. rectangular rod-carbon of suitable size. A layer of such rods, 13, is pressed into place in contact with the back plate 11, and pressed into effective contact therewith by metallic bars, 14, triangular in cross section, driven through the meshes of the ex 'ianded-metal. .Anoth'er set of carbon rods, 15,- is then placed tnre, having said plate 1.1 as its base, is incorporated in the carbon lining of the hearth, as shown in Fig. 12, and the disk 10 of the stem 10 is bolted thereto. Suitable provision is made for cooling the electrode stem 10, as indicated by the water chamber 17, Fig. 12, within the. disk 10 and the stem proper, and the water circulating pipes 18 and 19, the details of which may be of any known or improved description. The other electrode. stems may obviously be cooled in like manner. Said electrode stem 10 protrudes through a water-cooled slulling box, 20, mounted on a. face plate, 21, which is bolted to the bottom of the furnace, so as to 'be detachable and when detached ex )oses an opening, 22, through which the end disk 10' is introduced and withdrawn.

The secondary electrodes, 10, at the top of the furnace, are preferably four in number, located above the respective main electrodes (1, r, s and t, and preferably of the peculiar construction represented by Figs. 8, 9, 10 and 11. As shown in these figures, the body of each of these top electrodes to is composed mainly of carbon rods, 23, arranged vertically within a rectangular metallic holder, 24, one of the longer faces of which is open to expose the carbon body. Clamp plates, 25, of expanded metal, or the like, are cast fast within each holder 24: in pairs parallel to its sides. The carbon rods, 23, are placed within the holder, 24:, layer upon layer, between said cla'mp plates, The spaces between the rods are filled with packings, 26, of carbon cement; and the rods, 23, are held in place by the sides and lower end of the holder 24:, and by becoming cemented into a solid composite mass. The metallic stem, 27, of each of these electrodes, is attached to the carbon holder, 24-, and extends upward through a water-cooled stuffing box, 28, on the top plate (Z as shown in Figs. 1 and 4:, and in Fig. 8. Said bodies of the top electrodes w, or the top electrodes proper, including the carbon rods of each and their holders, are supported subjacently within rectangular pockets, 29, Figs. 1, 5 and 8, formed in the walls of the central coke passage 2', so that the face of the carbon body of each of these electrodes is substantially flush with the inner surface of said wall, and in contact with the charge of coke through which the electric current pas es from the bottom electrode 'v to the top e ectrodes w, the latter being of one polarity.

The two sets of electrodes, that is to say the main electrodes, q, r, s, t, and the secondary electrodes, 7), w, are preferably connected electrically with different dynamos; and the latter are preferably of the two-phase or alternating type, for the main electrodes at least. The bottom electrode 0; forms the lining, as aforesaid, of a hearth M, which is made of ample capacity and is located immediately beneath the main electrodes q, r, s, and z, and provided with an outlet, 30, through which to run oit the iiuid metal, and an outlet, 31, ata. higher point, for molten slag. The hearth portion of the furnace is suspended from an annular metallic sill, 32, which may rest upon columns or the like in customary manner, and the depending portion of the hearth is provided with a water jacket, 33, provided with suit ably located inlet and outlet connect-imis, 34 and 35, Fig. 1.

An annular gas chamber, 36, Fig. 1, etc., at the top of the furnace, communicates freely with the coarse-ore and coke passages, and with the intermediate passages for fine ore and regulating material, and discharges through an outlet pipe, 87, Figs. 1, 4 and For circulating the gases within the furnace, with reference to promoting the reduct ion of oxid iron ore in the manner hereinbefore described, the gas spaces m formed within the several fine-ore sections of the furnace, as shown in Figs. 2., and G,-C( 111'- municate as already mentioned with tubes 0. These tubes 0 extend through the inner fineore passages (in) from the coarse-ore passages j, outward into curbs, 38, which project inward to such gas spaces at from outside the furnace; and rotary {t lowers,; 9, in the form of electric fans, are located within the outer ends of said tubes and driven by electric motors, 41:, attached to the iron shell I) of the furnace; the operation being to draw through the ore' into said gas spaces on the carbonic oxid gas, CO, formed at and in the vicinity of the heat zone, and to force the resulting carbonic acid, CO through the coarse ore into the central column of hot -coke, by which it is again reduced to carb0nic oxid gas, so

repetition of this reaction suthciently to reas to' render possible the duce the fine ore to a considerable extent as it escapes from beneath the bafiie plates ,1), through the openingsp, on its way to the heat zone and before reaching the hottest part of the furnace. The blower tubes 0 are so'located as to keep the blowers w from opposing one another, as represented in Figs. 3 and 15, which see. Those portions of the blower tubes 0 extending through the inner fine-ore passages (in) operate as battles, and supplement the baflle plates The columns of coarse ore and coke within the working chamber of the furnace are separated initially at top by partitions formed as already indicated by flying buttresses sprung between the wall of the working chamber 71- and within whi cated. Compare Figs. 1, 2 and 3, and Fig. 6. The initial separation of the columns thus insured perpetuates itself downward, within ward through the the central circular wall ch the top electrodes to are 10- the working chamber 21, as indicated in Figs. 1 and 2, where the charge of the furnace is represented in the plane of section.

The regulating material descending by gravity through its passages Z, as shown in Fig. 1, tends by its greater weightto feed itself beneath the superjacentwings of the coke column, upon and between the main electrodes, r r, s, 1;, as shown in this figure; and the several streams may be manipulated, if desired, to increase or lessen their effectin regulating the operation of the furnace, by means of suitable stokers provided with insulated handles and introduced through the stoke holes 4, Fig. 1, before mentioned. The fire-ore passages -70 and gas spaces m, terminate at bottom in open ends within arched recesses, Figs. 9., etc., as clearly shown in Fig 3. Thefine ore thus released tends to fall inward to a greater or less extent as indicated in Fig. 2, and any particles which may enter with the gases into the gas spaces mare immediately discharged therefrom so as to keep said spaces clear.

T o insure the inward feed of the ore to a sufiicient extent, suitable stokin means are provided beneath the several ne-ore pas sages 7c. Such means may consist of stoking screws, 2 or 2", Figs. 2, etc., and Fig. 21, as shown in the drawings. Thefine ore, descending by gravity to the plane of these stokin g screws 2 or a", is there forced inward toward the heat zone, as represented in Fi 2, carrying with it and intermin ling with more or less of the coarse ore. Ti screws 2; are rotated for this purpose by means of worm gearing, 40, which may be e stoking' driven by hand cranks or by electric motors.

Compare Figs. 2,3, 7, 16 and 17. The screws 2 have their main bearings in water-cooled stuthng boxes, 41 and outer bearin 's' within yokes, 42, attached to the face p iates, 48, which support said stuffing boxes and between which and the iron shell I) water cooled frames 44, and ample insulation are interposed. Each of the screws is also'co'nstructed with a section, 45, of insulating material, interposed between the inner portion of the screw and its outer stem, 46, 'to prevent the passage of the electric current out screws. The inlet and outlet water connections of each stufling box, 41, and each water-cooled frame 44 are represented respectively in Figs. 16 and 17 at 4748 and 49-50. The openings capped materials at or in the proximity of the focus of the furnace, the inner and outer stems of the working screws slsggg-at 2 are provided with axial passages 52, Figs. 16 and 17, and the outer stems 46 are connected by swivel couplings 53, with hose or pipes, 54, through which air or other suitable oxidizing material may be blown into the center of the working chamber a at will.

Separate twyers, 2, Fig. 21, ma be provided additional to or in lieu of a ove provision lor introducing oxidizing material through "the stoking screws 2, and, especially if such twyers be provided as substitutes for that provision, hollow-stemmed stoking screws, 2 Fig. 21, may be employed, with water connections 5(3 for cooling them; suitable provision being made against any leakage of water or steam into the working chamber a. Either type of stoking screws may be horizontal as represented at 2, or set at an angle so as to feed downwardly as rep resented at 2 Fig. 21.

One or more man holes, 57, Figs. and 3, suitably capped, and conveniently located beneath one or more of the stoking screws .2, provide for entering the furnace after it is emptied and cooled for the renewal or repair of the electrodes and other like work, and may also be utilized in arranging the charge preliminarily. In preliminarily charging the furnace, the ,hearth a is filled with coke, and a column of coke is built up within the working chamber a surrounded by coarse ore to a suiiicient height to insure the completion of a continuous coke column extend ing from the bottom electrode 4; to a point more or less near the upper ends of the top electrodes 10. Simultaneously, after the plane of the main electrodes, 1, r, s, 2", is reached, fine ore may be fed in through the fine-ore hoppers, y until the fine-ore passages, k, 7;, are filled or substantially filled. The passages, Z, for regulating material, above the several main electrodes, 9, r, s, it, may be filled at the same time or subsequently, and the streams oi regulating material may be suitably directed over and in contact with the main electrodes, as shown in Fig. 1.

The electric current is turned on, first through the secondary electrodes '0 and 'w, as illustrated diagrammatically by Fig. 18,

and through the lIltCI'VOIllDg column of coke, The

which is thus rendered incandescent. current is then turned on through the main electrodes, z r, s, t, and its supply to both sets from different dynamos as aforesaid, may be siinullaneousas illustrated diagranr niatically by Fig. 19. The current/may thus be passed through the charge by way of all the electrodes throughout the reducing operation, or the secondary electrodes, 41*10, may be used only occasionally as required. The gas circulating blowers, w, are started as soon as the coke column is incandescent, so as toinsurc the conversion of the carbonic-oxi .l gas formed in the vicinity of the heat zone into carbonic acid, and the conversion of the latter into carbonic-oxid gas again, and so on alternately as above described. Suitable fluxes are added to the several columns of ore and possibly to the coke, as may be required, and the supply of materials by way of the several hoppers, e, f, g, h, at the top of the furnace, is kept up so as to render the operation of the furnace substantially continuous.

Stoking at the stoke holes 1, Fig. 1, is resorted to occasionally as may be required to render the operation of the main electrodes, q, r, s, 25, substantially uniform; and the stokingscrews 2 or a are operated from time to time as may be required to regulate the feed of the line ore inward to the heat zone. The fluid metal is run oil from time to time or continuously through the tap hole, 30, Fig. 1, and the molten slag through its outlet 31, Fig. 1. The discharge of gas through the pipe 37 at the top of the furnace may. be continuous, and may, if desired, be promoted by an exhaust fan; the gas being stored, for use in engines or otherwise, in known or improved ways.

The electric connections may include suitable switches .tor varying the How of the current through the main electrodes, 9, r, 8, t, as illustrated by Fig. 12 of my drawings forming part of United States Patent No. 702,117, dated June 10, 1902; and in like manner provision may be made for disconnecting the main electrodes from their normal source of supply and throwing them into circuit with the bottom electrode 7), as illustrated by Fig. 20, in order to melt out the contents of the hearth a after temporarily suspending the operation.

Suitable carbonaceous material will in most cases be mixed with the ore, and other mixtures may obviously be fed into the working chamber through the several hoppers at the top of the furnace to produce alloys or otherwise to regulate or vary the product of the furnace. For example, large pieces or chunks of electrode carbon may be fed into the central hopper e occasionally or systematically, so as to become parts of the coke column and to feed slowly downward therein, with reference to their accumulation to a suliicient extent between the main electrodes, g, "r, .s', t, to hold back one of more of the materials for reduction, and to insure proper conductivity without obstructing the trickling of streams of the molten metal downward between the electrodes into the hearth. Instead of being strictly horizontal as shown, the main electrodes, 9, r, s, a, may be inclined at any angle found practicable or necessary to their best operation. Such inclined electrodes, being in all cases more nearly horizontal than vertical, are intended to be included in the terms horizontal electrodes, and horizontal main electrodes.

The hearth (a) maybe shallow and in-v clined, so as to allow the reduced metal and slag to flow continuously from the furnace,

into an outside settling chamber,- there to complete their separation from each other, as is common practice in ordinary copper and lead smelting furnaces.

In practice all the electrode stems will be water cooled in substantially the manner shown at 17, 1S and 19 in Fig. 12; and the face plates 8 and 21, or the former at least, will be separated from the iron shell Z) by water-frames substantially as shown at 44, 4S) and 50 in Fig. 16.

()ther stoking means may obviously be employed inplace of the stoking screws above described; and other like modifications will suggest themselves to those skilled in the art.

Having thus described said improvement, I claim as my invention, and desire to patent under this specification:

1. In an electric smelting furnace having horizontal electrodes and a body of stack form containing a working chamber into which said electrodes extend, and provided with a central flue-shaped feed passage extending vertically downward toward the plane of said electrodes and like feed passages extending downward around said central passage toward the same plane, the com bination of a top plate constructed with feed opei'iings in communication with said passages respectively, and superposed hoppers the walls of which are constructed and rigidly connected with eachother and with said top plate to form'trusses to stiffen and support said top plate.

2. An electric smelting fnrnace'having, in combination; horizontal electrodes, and a body of stack form containing a central working chamber into which said electrodes extend, a central flue-shaped passage above said working chamber, wing forming passages adjoining said central passage and feed passages surrounding said central passage and separated from eachother by said wing forming passages, said passages dis-- charging 111 common into said working chamber above said electrodes.

An electric smelting furnace having, in combination, horizontal electrodes, and a body of stack form containing a central working chamber into which said electrodes extend. a central flue-shaped coke passage extending vertically downward toward the plane of said electrodes, coarse ore and fine orepassages extending downward around the same, and means for gradually mixing the tine ore with the coarse ore on its way to the heat zone.

An electric smelting furnace having. in

bodyv of stack form containing a central working chamber into which said electrodes extend, a central flue-shaped coke passage extending vertically downward toward the plane of said electrodes, coarse ore passages extending downward around said coke passage and fine ore passages external to said coarse ore passages, whereby outwardly directed heat is intercepted and utilized for heating fine ore.

5. An electric smelting furnace having, in combination, horizontal electrodes, a suitably lined metallic shell through which said electrodes extend inward and which incloses the working chamber, and an inner structure of brick or the like forming a central flue-shaped coke passage, coarse-ore. passages extending downward around the same and fine-ore passages external to said coarseore passages within said shell, whereby outwardly directed heat is intercepted and utilized for heating the fine ore.

6. An electric smelting furnace having, in combination, horizontal electrodes. a suitably lined metallic shell through which said electrodes extend inward and which incloscs the'working chamber, and an inner structure of brick or the like forming a central tlueshaped coke passage, coarse-ore passages extending down ard around the same, fineore passages external to said coarse-ore passages and means for gradually mixing the fine ore with the coarse ore on its way to the heat zone.

7. An electric smelting furnace having, in combination, horizontal electrodes, a suitably lined metallic shell through which said electrodes extend inward and which inc-loses the working chamber, and an inner struc ture of brick or the like forming a central flue-shaped coke passage, coarse-ore passages extcnding downward around the same, fine-ore passages external to said coarse ore passages within said shell, and'an inner wall forming the wall of the working chamber and provided with openings through which the fine ore may flow gradually into the working-chamber and become mixedwith the coarse ore.

8. An electric smelting furnace having, in combination, horizontal electrodes. a suitably lined mctallic shell through which said electrodes extend inward and which incloses the working chamber, and an inner structure of brick orthe like forming a central flueshaped coke passage, coarse-ore passages extending downward around the same. tine-ore passages external to but adjoining said coarseore passages and comn'iunica.ing therewith at intervals for the gradual till-- mixture of the line ore with the coarse ore, and peripheral fine-ore passages discharging at bottom into the working chamber, where by a relatively solid body of fine ore is an interception and utilization of outwardly directed heat.

9. An eleetrie smelting furnace having, in combination, horizontal electrodes, a suitably lined metallic shell through which said electrodes extend inward and which ineloses the working chamber, and an inner structure of brick or the like forming a central tlueshapcd coke passage, 1mssages arranged to form wings of the coke column above the respective electrodes, and ore passages separated by said wing-forming passages, said passages in common communicating with the working chamber at bottom and adapted to feed material downward by gravity.

It). An electric -'melting lurnace having, in combination, horizontal electrodes, a. suitably lined metallic shell through which said electrodes extend inward and which ineloses the working chamber, and an inner structure of brick or the like t'orming a central flue-shaped coke passage, passages arranged to term wings oil the coke column above the respective electrodes, and ore passages sepa atcd by said wing-forming passages, said passages in common communicating with the working chanibe at bottom and adapted to feed the materials downward by gravity, and passages for resistantic-regulating material external to said wing-forming passages discharging downward upon the respective electrodes.

11. An electric smelting furnace having, in combination, horizontal. elect rodcs. a suitably lined metallic shell through which said electrodes extend inward and which incloses the working chamber, an inner structure of brick or the like forming a central flueshaped coke passage, coarse-ore passages extending downward around the same and fine-ore passages external to said coarse-ore passages within said shell, and means for stoking the fine ore beneath said fine-ore passages and above the plane of said electrodes.

12. An electric smelting furnace having, in combination, horizontal electrodes, a suitably lined metallic shell through which said electrodes extend inward and which incloses the working chamber, an inner structure of brick or the like forming a central flue-shaped coke passage, coarse-ore passages extending downward around the same and tine-ore passages external to said coarse-ore passages within said shell, stoking screws extending inward beneath said fine-ore passages and above the plane of said electrodes, and means for supporting and rotating said stoking screws attached to the shell of the furnace.

13. An electric smelting furnace having, in combination, horizontal electrodes, a suitably lined metallic shell through which said electrodes extend inward and which ineloses the working chamber, an inner structure of brick or the like forming a central flueshaped coke passage, coarse-ore passages extending downward around the same and tine-ore passages external to said coarse-ore passages within said shell, stoking screws extending inward beneath said tine-ore passages and above the plane oi said electrodes and adapted for the introduction of oxidizing material therethrongh into the center of the working chamber, and means for supporting and rotating said stoking screws attached to the tell of the furnace.

ll, An electric smelting furnace having, in combination, horizontal electrodes, a suitably lined metallic shell through which said electrodes extend inward and which incloscs the working chamber, an inner structure of brick or the like forming a central lineshaped coke passage, coarse-ore passages extending downward around thesame. and line ore passages external to said coarse-ore passages within said shell, stoking screws extending inward beneathsaid tine-ore passages and above the plane of the electrodes and constructed with axial passages within their stems, pipes connected with the outer ends of said stems by swivel couplings for the introduction thcrethrough of oxidizing material, and means [or supporting and rotating said. stoking screws attached to the shell oi" the ,t'urnace.

15. An electric smelting turnace having, in combination, h-u'i'zoutal electrodes, a body oil stack t'orm containing the working chan1- her into which said electrodes extend and provided with a cei'itral flue-shaped coke )assage and with flue-shaped coarse-ore and tine-ore passages surrtmnding said coke passage within the upper part of said body through which the materials for the charge may flow continuously downward toward the plane of said electrodes, and a snbjacent hearth adapted for the discharge of the metal and slag in fluid condition.

16. An electric smelting furnace having, in combination, horizontal electroch s, a body of stack form containing the Working cham her into which said electrodes extend and provided with a central flue-shaped coke passage and with flue-shaped coarse-ore and tine-ore passages surrounding saidcoke passage within the npper part of said body through which the materials for the charge may flow continuously downward toward the plane of said electrodes, and a subjacent water-jacketed hearth provided with a tap hole and a slag outlet.

1.7. An electric smelting furnace having, in combination, horizontal electrodes, a body of stack form containing a central working chamber into which said electrodes extend and provided with a central flue-shaped feed passage and feed passages on all. ides around said central passage within the upper part of said body through which the materials for the charge may tlow continuously down- I ward toward the plane of said electrodes, at

subjacent hearth adapted for the discharge of the metal and slag in fluid condition, an annular gas chamber at the top of the furnace in communication with the passages last named, and a pipe leading therefrom for the utilization of the gaseous by-product.

18. An electric smelting furnace having, in combination, horizontal electrodes, a body of stack form containing a central working chamber into which said electrodes extend and provided with a central vertical coke passage within the upper part of said body, coarseore passages extending downward around said coke passage and fine-ore passages extending downward external to said coarse-ore passages, said passages discharging in common within said working chamher, a subjacent hearth adapted for the dis' charge of the metal and slag in fluid con dition, an annular gas chamber at the top of the furnace in communication with said coarse-ore passages and said fine-ore passages, and a pipe leading therefrom for the utilization of the gaseous by-products.

19. An electric smelting furnace having, in combination, horizontal electrodes, a body of stack form containing a central Working chamber into which said electrodes extend and provided with a central vertical coke passage, passages forming Wings of said coke passage above the several electrodes, passages external to said wing forming passages for feeding resistance regulatin material and ore passages at the sides 0 said wing forming passages and passages for resistance regulatin material, a subjacent hearth adapted for the discharge of the metal and slag in fluid condition, an annular gas chamber at the top of the furnace in communication with said ore passages and with said wing forming passages and passages for resistance regulating material, and a pipe leading therefrom for the utilization of the gaseous by-product.

20. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the Working chamber, hori zontal electrodes extending inward through said shell and arranged in two airs at right angles to each other, means or passing a two phase current through the respective pairs of electrodes and thusdividing the working chamber into quarters, means for supplying the respective quarters with ore fed by gravity, and means for maintaining a central gravity-fed coke column within the working chamber.

21. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, hori zontal electrodes extending inward through said shell and arranged in two pairs at right angles to each other, means for passing a two-phase current through the respective pairs of electrodes and thus dividing the working chamber into quarters, means for supplying the respective quarters with coarse ore fed by gravity, means for mixing therewith fine ore fed independently toward the heat zone by gravity, and means for maintaining a central gravityfed coke column within the working chamber.

22. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, horizontal electrodes extending inward through said shell, means for supplying the working chamber with ore fed by gravity in the form of columnsat the sides of the several electrodes, and means for separating the columns of ore includin Y inner walls forming a central vertical c0 e passage and laterally ex-,

- stack type having, in combination, a suitable shell inclosing the working chamber, horizontal electrodes extending inward through said shell and arranged in two pairs at right angles to each other, and means for feeding materials for the reaction in the form of a coke column cruciform in cross section with ore columns in its rentrant angles.

24. An electric; smelting furnace of the' stack type havin in combination, a suitable shell inclosing the working chamber, horizontal electrodes extending inward through said shell and arranged in two airs at right angles to each other, means or passing a two-phase current through the respective pairs of electrodes and thus dividing the working chamber into quarters, means for supplying the respective quarters with ore fed by gravity, and means for separating the columns of ore including inner walls forming a central vertical coke passage and laterally extending wings of the same ex tending downward between the ore columns.

25. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, horizontal electrodes extending inward throu h said shell and arranged in two airs at right angles to each other, means or passing a two-phase current through the respective pairs of electrodes and thus dividing the working chamber into quarters, means for supplying the respective quarters with ore fed by gravity in the form of flue-shaped passages within the upper part of the shell,

I able shell inclosing the working chamber,

horizontal electrodes extending inward through said shell and arranged in two pairs at right angles to each other, means for passing a two-phase current through the respective pairs of electrodes and thus dividing the working chamber into quarters, and walls within the upper part of said shell forming flue-shaped passages for supplying, the respective quarters with ore fed by gravity and walls formin a central coke passage and wing-shaped co e passages above the several electrodes, the walls forming said central and wing-shaped passages serving to sparate the ore columns in the upper part of the furnace and to insure their separation to a sufiicient extent below said walls by the coke column and its wings.

27. An electric smelting furnace of the stack type having, in combination, a suit-able shell inclosing the working chamber, horizontal electrodes extending inward through said shell and arranged in two pairs at right angles to each other, means for passing a two-phase current through the respective pairs of electrodes andthus dividing the working chamber into quarters, and inner walls within the upper part of the shell forming flue-shaped passages for the supply of the respective quarters with ore fe gravity, a central coke passage, wing-shaped coke passages adjoining said central passage and passages between said wing-shaped passages and the shell through which resistance-regulating material may be fed downward upon and between the electrodes.

'28. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, horizontal electrodes extending inward through said shell and arranged in two pairs at right angles to each other, means for passin a two-phase current through the respective pairs of electrodes and thus dividing the working chamber into quarters, means for s gpplying the respective quarters with ore by gravity including walls forming fluesha ed passages within the upper part of the she l, and Walls forming a central coke passage, passages forming wings oi the coke column above the several electrodes, and passages nearer the shell through which resistance-regulatingmaterial may be fed downward upon and between the electrodes; said shell being provided with stoke holes above the several electrodes in communication with working chamber beneath the passages last named.

An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, horiaontal main electrodes extending inward through the sides of said shell, secondary electrodes located respectively at its top and bottom, and means for feeding the material for the charge including inner walls forming a flue-shaped coke passage through which a column of carbonaceous material is fed downward to form a resistance conductor between said' secondary electrodes.

30. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, horizontal main electrodes extending inward through the'sides of said shell, secondary electrodes located respectively at its top and bottom, and means for feeding the material for the charge including inner walls forming a flue-shaped coke passage through which a column of carbonaceous material is fed downward to form a resistance conductor between said secondary electrodes and walls forming downwardly extending ore passages separated from each other by said coke passage.

31. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the Working chamber, horizontal main electrodes extending inward through the sides of said shell, secondary electrodes located respectively at its top andbottom, and means for feeding the material for the charge including inner walls formin a central flue-shaped coke passage through which a column of carbonaceous material is fed downward to form a resistance conductor between said secondary electrodes and walls forming downward extending passages for coarse and fine ore respectively, located at the sides of said coke passage, the fine ore passages being arranged outermost for the conservation of outwardly directed heat.

32. An electric smelting furnace of the stack type having, in combination, a suitable shell inclosing the working chamber, horizontal main electrodes extending inward through the sides of said shell, secondary electrodes located respectively at its top and bottom, and means for feeding the material for the charge including inner walls forming a central flue-shaped coke passage through which a column of carbonaceous material is fed downward to form a resistance conductor between said secondary electrodes, said secondary electrodes at the top of the furnaoe being arranged at the sides of said coke passage and exposed to contact with the matgrial within said passage.

33. An electric smelting furnace of the stack type havin in combination, a suitable shell ,inclosing t e working chamber, horizontal main electrodes extending inward through the sides of said shell, secondary electrodes located respectively at its top and bottom, and means for feeding the material for the charge including inner walls forming a central flue-shaped coke passage through which 'a' column of carbonaceous material is fed downward to form a resistance conductor between said secondary electrodes, said secondary electrodes including a plurality of 

